Atomizing burner for a heating device of a vehicle

ABSTRACT

The invention relates to an atomizer burner for a motor vehicle heater, with a cobustion chamber which contains a baffle barrier and with an atomizer means ( 2 ) which atomizes the fuel into the combustion chamber, characterized in that within the combustion chamber in the atomization direction of the fuel at a distance from the atomization point of the atomizer means ( 2 ) which is smaller than the diameter of the combustion chamber or the diameter of a cylindrical heat shield ( 8 ) which extends in the combustion chamber there is a baffle plate ( 18 ) which acts as a baffle barrier.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an atomizer burner for amotor vehicle heater. In particular, the present invention relates tosuch an atomizer burner having a baffle plate.

2. Description of the Related Art

Atomizer burners with which the energy bound in fossil fuels can beconverted into heat energy are already in use in the various fields asexemplified by the International PCT document WO 87/00605 or thepublished German Patent Application DE 39 01 126 A1. In the area ofmotor vehicle heaters, atomizer burners or nozzle atomizer burners inthe power range of less than (<) 10 kW are generally not used, since theatomization quality is not considered sufficient at smaller powers and ahigh electric power consumption is necessary to achieve adequateatomization quality. In addition, atomizer burners exhibit poorcombustion characteristics in the partial load range since in such loadrange, the atomization quality is poorer than under a full load.

Finally, nozzle atomizer burners of the known type exhibit poor coldstarting behavior, because based on the viscosity of the fuel whichincreases as the temperature decreases, the atomization quality isadversely affected. Here, large fuel droplets pass unvaporized or onlypartially vaporized through the combustion chamber part thus causinghigh starting emissions. A poor exhaust gas quality, if only during thestarting phase, cannot be tolerated nowadays with consideration of theincreased sensitivity of the market with respect to environmentalissues.

SUMMARY OF THE INVENTION

Thus, in view of the above, the primary object of the present inventionis to provide an atomizer burner for a motor vehicle heater which, evenat lower powers in the partial load range and during the cold startphase, still provides good combustion behavior and low emissions.

This object and other advantages are achieved by the embodiments of thepresent invention described below.

In accordance with one embodiment of the present invention, an atomizerburner for a motor vehicle heater is provided with a combustion chamberpart which contains a baffle barrier, and with an atomizer whichatomizes the fuel into the combustion chamber part. Baffle plate whichacts as a baffle barrier is provided at a distance from the atomizationpoint of the atomizer which is smaller than the diameter of thecombustion chamber part or the diameter of a cylindrical heat shieldwhich extends in the combustion chamber part. The baffle plate whichacts as the baffle barrier has the effect of flame stabilization whichacts advantageously to reduce flame noise and the improve combustion,especially at smaller powers or in the partial load range of the burner.The baffle plate is especially advantageous in the implementation ofcompact combustion chambers for liquid fuels. The burner equipped withthe baffle plate can process even poorer atomization qualities by theplate without this adversely affecting the combustion behavior.Therefore, the present invention allows improved implementation ofpartial load stages in which the atomization quality is poorer than inthe full load stage.

The baffle plate can be conical, convex, or concave shaped, among othershapes. The arrangement of the baffle plate in the flame zonefacilitates re-ignition of the fuel on the glowing disk after flameblow-off, which may be caused, for example, by air bubbles in the fuelline. In addition, CO and HC emissions can be reduced when thecombustion process ends by the fuel reacting on the glowing baffleplate.

The baffle plate can be made as a disk with a collar with a height of 2mm for instance, which extends against the atomization direction of thefuel so that it forms a cup shape which is open to the atomizer. Theratio of the baffle plate diameter to the fuel chamber diameter ispreferably between 0.6 and 0.9, and the ratio of the axial distance ofthe baffle plate from the atomization point to the combustion chamberpart diameter is preferably between 0.3 and 0.6. Suitable dimensioningof the baffle plate, compared to the other aerodynamic measures, yieldsonly a slightly increased pressure loss in the combustion chamber part.For example, the tangential component of a combustion air flow which isdelivered with a swirl is only insignificantly disrupted, so that thecombustion gases can also flow downstream of the baffle plate stillhaving a swirl component. The baffle plate is preferably fixed withmounting clips.

In one embodiment, the baffle plate can have openings in the form ofslots and/or holes, the openings being made preferably in the form ofdefined perforation of the baffle plate. However, the baffle plate canalso be made as a ring with a central through hole.

Furthermore, in one especially preferred embodiment, a chamber isprovided on the baffle plate into which a glow means in the form of aglow pin, for example, of ceramic, or in the form of a glow plug,projects. By providing such an arrangement of the glow means in the areaof the restricted flow upstream of the baffle plate, the startingbehavior of the burner is thereby improved. The chamber is preferablymade such that the glow means projects into it so that the radiantenergy of the glow means can be used downstream of the atomizationdevice to heat the components of the baffle plate. In this way, thestarting characteristics of one such burner is greatly improved.

The baffle plate can, among others, be fixed on the combustion chamberpart, on the combustion chamber bottom, or on aerodynamic internals, forexample, a swirling device for the combustion air.

The baffle plate may preferably be made of high-alloy steel, of ceramicor of ceramic-coated steel.

These and other advantages and features of the present invention willbecome more apparent from the following detailed description of thepreferred embodiments of the present invention when viewed inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional view an atomizer burner in accordancewith one embodiment of the present invention;

FIG. 2 shows a perspective view of a combustion chamber part with aflame tube in accordance with one embodiment;

FIG. 3 shows a cross-sectional view of the combustion chamber part shownin FIG. 2;

FIG. 4 shows an overhead view of the baffle plate of the combustionchamber part shown in FIG. 2;

FIG. 5 shows another embodiment of the atomizer burner of FIG. 1 butwith a concave baffle plate;

FIG. 6 shows yet another embodiment of the atomizer burner of FIG. 1 butwith a convex baffle plate; and

FIG. 7 shows still another embodiment of the atomizer burner of FIG. 1but with a conical baffle plate.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a cross sectional view of one preferred embodiment of anatomizer burner 1. The atomizer burner 1 of this embodiment includes anatomizer such as the atomizer nozzle 2 to which an air-guide 4 thatswirls the combustion air entering the atomizer nozzle 2 is connected inseries. Of course, in other embodiments, other types of atomizers may beused as well. Upstream of the air-guiding device 4, on the left side inthe illustrated example, there is a fuel feed line 6 through which thefuel to be atomized in the atomizer such as the shown atomizer nozzle 2is supplied. The atomizer nozzle 2 is connected to the cylindrical heatshield 8 on its side facing the combustion chamber part 24 which isshown in the embodiment of FIG. 5. This heat shield 8 can be providedwith secondary air openings 10 which are also provided in the flange 12located upstream of the heat shield 8 which can also be used to attachthe atomizer nozzle 2 within the combustion chamber part or within themotor vehicle heater. The secondary air which passes through these holes10 is subjected to a swirl by the air-guiding swirling device 14. Theatomizer burner 1 shown in the present embodiment is also provided witha glow means 16 with which the atomized fuel mixture is ignited, theglow means 16 preferably being a glow pin or a glow plug made of aceramic material. Optionally, in addition to the glow means 16, there isalso provided an ignition means (not shown) which may be used to producean ignition spark as practiced in conventional atomizer burners.

As also shown in the embodiment of FIG. 1, on the heat shield 8 of theburner 1, there is a baffle barrier in the form of a baffle plate 18which is flat in the illustrated example, the baffle plate 18 beinglocated perpendicular to the lengthwise axis of the combustion chamberpart 24. Fuel which is atomized in the atomizer nozzle 2 and which canemerge in the form of fuel droplets due to inadequate fuel preparation,strikes the baffle barrier which is made as a flat baffle plate 18 andcan vaporize there on the baffle plate. The baffle barrier, in thiscase, the baffle plate 18, is located within the flame zone of theburner so that flame stability is improved. Moreover, the baffle plate18 acts to deflect the flow and thus, to stabilize the flame.

The baffle plate 18 is preferably made of high-alloy steel and may bemade as a disk having a collar 20 roughly 2 mm in height which extendsagainst the atomization direction of the fuel so that it forms a cupshape which is open to the atomizer nozzle 2. Alternatively, the baffleplate 18 can also be made of ceramic material or a high-alloy steelcoated with a ceramic material. As can also be seen in FIG. 1, thebaffle plate 18 is attached to the heat shield 8 using mounting clips22.

Other embodiments of baffle plates are discussed herein below referringto various figures which show the burner with the various embodiments ofthe baffle plates. It should be noted that the in these figures, commonnumerals are used to identify common components, the various embodimentsof the baffle plates being distinguished using letter designations A, B,C and D.

FIG. 2 is a perspective view of a combustion chamber part 24 which isprovided with a baffle plate 18D, there being a flame tube 26 on theback of the combustion chamber part 24. The baffle plate 18D which ismade in this embodiment as a disk with a central through hole 34 so asto have a ring shape, is attached via mounting clips 22 in thecombustion chamber part 24. As shown furthermore by FIG. 2, on thebaffle plate 18D, there is a starting chamber 28 into which a glow meanscan project. Areas of the baffle plate 18D may be used as a “hot-spot”in order to heat the starting chamber 28 or the baffle plate 18D. Inaddition, the starting chamber 28 is also used as a damping zone inwhich a pilot flame is formed more quickly and which accelerates thevaporization of the atomized fuel, thus leading to faster ignition whenthe burner starts.

As is apparent, the starting chamber 28 in this embodiment is located onthe edge of the baffle plate 18D. Alternatively, it can also be attachedat any other point on the baffle plate, especially when the baffle plate18 is flat, or can be made molded with it. The position of the startingchamber 28 is ultimately determined by the position of the glow means.

The combustion chamber part 24 in FIGS. 2 to 4 is combined with theburner 1 such as that shown in FIG. 1 such that the heat shield 8 isinserted preferably inside into the combustion chamber part 24, againthe baffle plate 18 being attached in the present embodiment to thecombustion chamber part 24. Thus, the baffle plate 18 may be attached tothe heat shield 8 as shown in FIG. 1, or alternatively, be attached tothe combustion chamber part 24 as is shown in FIGS. 2 to 4. The heatshield 8 may also be mounted on the combustion chamber part 24, in thiscase there being recesses in the heat shield 8.

In the embodiment of the baffle plate 18 shown in FIG. 4, the baffleplate 18 is provided with holes 30 and slots 32. These holes 30 andslots 32 are optional. The baffle plate 18 in various embodiments maythus be provided with a given pattern of holes, with only one or moreholes 30, with one or more slots 32, or as shown, with combinations ofholes 30 and slots 32.

In the embodiment of the atomizer burner 1 shown in FIG. 5, the baffleplate 18A is concave in shape. Furthermore, as previously noted, thisfigure shows the combustion chamber part 24 which surrounds the outsideof the heat shield 8. In this regard, it should be noted that the otherillustrated embodiments also include such combustion chamber part 24 aswell but have been omitted for clarity.

In the embodiment of the atomizer burner 1 shown in FIG. 6, the baffleplate 18B is made convex in shape, i.e. with an arch pointed in adirection opposite the atomizer nozzle 2.

In the embodiment of the atomizer burner 1 shown in FIG. 7, the baffleplate 18C is made conical in shape. Of course, in another embodiment,the tip of the cone of the baffle plate 18C can also be pointed in adirection opposite to that shown.

In the various embodiments shown and discussed above, it is advantageousif the ratio of the axial distance of the baffle plate 18, 18A, 18B, 18Cand 18D from the atomization point P shown in FIG. 1 to the diameter ofthe combustion chamber part 24 is roughly between 0.3 and 0.6. Likewise,in the various embodiments shown and discussed above, it is advantageousif the ratio of the diameter of the baffle plate 18, 18A, 18B, 18C, and18D to the diameter of the combustion chamber part 24 or the diameter ofthe heat shield 8 located in the combustion chamber part 24 is roughlybetween 0.6 and 0.9. At these numerical ratios, very good combustionresults have been shown in operation.

The baffle plates described above which acts as the baffle barrier hasthe effect of flame stabilization which acts advantageously to reduceflame noise and the improve combustion, especially at smaller powers orin the partial load range of the burner. The baffle plate is especiallyadvantageous in the implementation of compact combustion chambers forliquid fuels. The burner equipped with the baffle plate can process evenpoorer atomization qualities by the plate without this adverselyaffecting the combustion behavior. Therefore, the present inventionallows improved implementation of partial load stages in which theatomization quality is poorer than in the full load stage. As describedabove, the baffle plate may be conical, convex, or concave shaped, amongother shapes. The arrangement of the baffle plate in the flame zonefacilitates re-ignition of the fuel on the glowing disk after flameblow-off, which may be caused, for example, by air bubbles in the fuelline. In addition, CO and HC emissions can be reduced when thecombustion process ends by the fuel reacting on the glowing baffleplate.

While various embodiments in accordance with the present invention havebeen shown and described, it is understood that the invention is notlimited thereto. The present invention may be changed, modified andfurther applied by those skilled in the art. Therefore, this inventionis not limited to the detail shown and described previously, but alsoincludes all such changes and modifications.

What is claimed is:
 1. Atomizer burner for a motor vehicle heatercomprising: a combustion chamber part within which fuel is combusted; anatomizer having an atomization point at which the fuel is atomized intothe combustion chamber part; and a baffle plate within the combustionchamber part, the baffle plate being positioned from the atomizationpoint of the atomizer at a distance which is less than the diameter ofthe combustion chamber part for vaporizing unatomized fuel dropletswhich emerge from the atomizer.
 2. Atomizer burner as claimed in claim1, further including a heat shield which extends into the combustionchamber part.
 3. Atomizer burner as claimed in claim 2, wherein thedistance of the baffle plate from the atomization point of the atomizeris less than the diameter of the heat shield.
 4. Atomizer burner asclaimed in claim 1, wherein the baffle plate is conical in shape. 5.Atomizer burner as claimed in claim 1, wherein the baffle plate isconvex in shape.
 6. Atomizer burner as claimed in claim 1, wherein thebaffle plate is concave in shape.
 7. Atomizer burner as claimed in claim1, wherein the baffle plate is a disk with a collar that extends in adirection opposite direction of atomization the fuel to form a cup shapeopen to the atomizer.
 8. Atomizer burner as claimed in claim 1, whereina ratio of the diameter of the baffle plate to the diameter of thecombustion chamber part is approximately between 0.6 and 0.9. 9.Atomizer burner as claimed in claim 2, wherein a ratio of the diameterof the baffle plate to the diameter of the heat shield located in thecombustion chamber part is approximately between 0.6 and 0.9. 10.Atomizer burner as claimed in claim 1, wherein a ratio of the distanceof the baffle plate from the atomization point to the diameter of thecombustion chamber part is approximately between 0.3 and 0.6. 11.Atomizer burner as claimed in claim 1, wherein the baffle plate has atleast one opening extending through the baffle plate, the at least oneopening being at least one of a slot and a hole.
 12. Atomizer burner asclaimed in claim 1, wherein the baffle plate is ring shaped. 13.Atomizer burner as claimed in claim 1, further including a glow meansfor igniting atomized fuel.
 14. Atomizer burner as claimed in claim 13,wherein the glow means is at least one of a glow pin and a glow plug.15. Atomizer burner as claimed in claim 1, wherein the baffle plate ismade of a high-alloy steel.
 16. Atomizer burner as claimed in claim 1,wherein the baffle plate is made of a ceramic.
 17. Atomizer burner asclaimed in claim 1, wherein the baffle plate is made of a ceramic-coatedsteel.
 18. Atomizer burner as claimed in claim 1, wherein said baffleplate is arranged perpendicular to a lengthwise axis of the combustionchamber part.
 19. Atomizer burner as claimed in claim 1, wherein saidbaffle plate is located in a flame zone of the combustion chamber part.20. Atomizer burner as claimed in claim 13, wherein said baffle plate islocated in a zone of radiant energy produced by the glow means. 21.Atomizer burner for a motor vehicle heater comprising: a combustionchamber part; an atomizer having an atomization point which atomizes thefuel into the combustion chamber part; a baffle plate within thecombustion chamber part, the baffle plate being positioned from theatomization point of the atomizer at a distance which is less than thediameter of the combustion chamber part; and a glow means for ignitingatomized fuel wherein the baffle plate includes a chamber into which theglow means projects.